lecture19-review of single transistor amplifiers
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Lecture19-Review of Single Transistor Amplifiers.pdfTRANSCRIPT
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1 Lecture19-Review of Single Transistor Amplifiers
EE105 – Fall 2014 Microelectronic Devices and Circuits
Prof. Ming C. Wu
511 Sutardja Dai Hall (SDH)
2 Lecture19-Review of Single Transistor Amplifiers
Terminal Resistance of Generally Loaded Transistors
BJT MOSFET
RC
RE
RB RD
RS
RG
Re =rπ + RB(β +1)
≈1gm
+RB
(β +1)Rb = rπ + (β +1)RERc = ro 1+ gmRE( )
Rs =1gm
Rg =∞
Rd = ro 1+ gmRS( )
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3 Lecture19-Review of Single Transistor Amplifiers
Single-Stage Amplifiers “Terminal Gain and I/O Resistances of BJT Amplifiers”
AV ,t = −gmRL
1+ gmRERi = rπ + (β +1)RERo = ro 1+ gmRE( )"# $%
AI ,t = β
Without degeneration:Simply set RE = 0
AV ,t =RL1gm
+ RL
Ri = rπ + (β +1)RL
Ro =rπ + Rth1+β
≈1gm
+Rthβ
AI ,t = β +1
AV ,t = gmRL
Ri =1gm
Ro = ro 1+ gmRE( )!" #$
AI ,t ≈1
For the gain, Ri, Ro of the whole amplifier, you need to include voltage/current dividers at input and output stages
4 Lecture19-Review of Single Transistor Amplifiers
Single-Stage Amplifiers “Terminal Gain and I/O Resistances of MOS Amplifiers”
AV ,t = −gmRL
1+ gmRSRi =∞
Ro = ro 1+ gmRE( )#$ %&
AI ,t =∞
Without degeneration:Simply set RS = 0
AV ,t =RL1gm
+ RL
Ri =∞
Ro =1gm
AI ,t =∞
AV ,t = gmRL
Ri =1gm
Ro = ro 1+ gmRE( )!" #$
AI ,t ≈1
For the gain, Ri, Ro of the whole amplifier, you need to include voltage/current dividers at input and output stages
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5 Lecture19-Review of Single Transistor Amplifiers
Single-Stage Amplifiers Simplified Characteristics of BJT Amplifiers
6 Lecture19-Review of Single Transistor Amplifiers
Single-Stage Amplifiers Simplified Characteristics of FET Amplifiers
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7 Lecture19-Review of Single Transistor Amplifiers
Inverting Amplifiers: C-E and C-S Amplifier Review
8 Lecture19-Review of Single Transistor Amplifiers
Follower Circuits Summay
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9 Lecture19-Review of Single Transistor Amplifiers
C-B and C-G Amplifiers Summary
10 Lecture19-Review of Single Transistor Amplifiers
Lower Cutoff Frequency (ωL) The SCTC Estimate: C-C Amplifier
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11 Lecture19-Review of Single Transistor Amplifiers
Lower Cutoff Frequency (ωL) The SCTC Estimate: C-C Amplifier (cont.)
Using the SCTC method:For C1:
R1S = RI + RB RiB( )R1S = RI + RB rπ + βo +1( ) RE R3( )!" #$
For C2 :
R2S = R3 + RE RiE( ) = R3 + RErπ + Rthβo +1
fL ≅1
2π1
R1SC1
+1
R2SC2
&
'(
)
*+
12 Lecture19-Review of Single Transistor Amplifiers
Lower Cutoff Frequency (ωL) The SCTC Estimate: C-D Amplifier
Using the SCTC method:
For C1:
R1S = RI + RG RiG( ) = RI + RG
For C2 :
R2S = R3 + RS RiS( ) = R3 + RS1gm
!
"#
$
%&
fL ≅1
2π1
R1SC1
+1
R2SC2
!
"#
$
%&